Calanthe densiflora Lindl.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 80-81

13. Calanthe densiflora Lindl.

Genera and Species of Orchidaceous Plants: 250 (1833) ; Hooker, Flora of British India 5: 855 (1890); Seidenfaden, Dansk Botanisk Arkiv 29: 22 (1975); Seidenfaden, Opera Botanica 114: 99 (1992); Pearce & Cribb, Flora of Bhutan 3 (3): 295 (2002); Chen et al., Flora of China, vol. 25: 295 (2009). — Alismorkis densiflora (Lindl.) Kuntze, Revisio Generum Plantarum 2: 650 (1891). — Type: India / Bangladesh border, Sylhet, Wallich s.n., Wallich’s Catalogue 7344 (holo-, K).

Phaius epiphyticus Seidenf., Nordic Journal of Botany 5: 159 (1985), syn. nov.; Seidenfaden, Opera Botanica 89: 44 (1986); Phukan & Mao, Orchid Review 110: 160 (2002). — Type: Thailand, Loei Province, Phu Luang , 1400-1500 m, 16.III.1980, Seidenfaden & Smitinand 8687 (holo-, C spirit!).

ADDITIONAL MATERIAL EXAMINED. — North-Eastern, Phetchabun, Suksathan 121 (BCU spirit). — North- Eastern, Phu Luang, Thaithong 481 (BCU spirit).

ILLUSTRATIONS. — Seidenfaden, Nordic Journal of Botany 5: fig. 2a-f, pl. 1a (1985) [as Phaius epiphyticus Seidenf. ]; Seidenfaden, Opera Botanica 89: fig. 20a-f (1986) [as P. epiphyticus Seidenf. ]; Seidenfaden, Opera Botanica 114: fig. 52a-c (1992); Phukan & Mao, Orchid Review 110: figs 126, 128 (2002) [as P. epiphyticus Seidenf. ].

DESCRIPTION

Terrestrial,?sometimes epiphytic herbs, evergreen, 40-60 cm tall, glabrous. Basal sheaths not seen. Pseudobulbs inconspicuous and largely hidden among the leaves, several-noded, covered by large dry sheaths, 2.5-6(-10) cm apart on an elongate wavy rhizome, its segments c. 0.5-1 cm thick. Leaves 2-4(-5), perennial, elliptic or oblong-elliptic, acute and acuminate, (18-)30-40 × 2-6 cm; with grooved petioles to 22 cm long (often much less). Inflorescences arching or suberect, arising next to the leafy shoots directly from the rhizome, less than half as long as the leafy shoot; peduncles 9-18 cm long; sterile bracts 2-5, erect, tubular and inflated, ovate-lanceolate or elliptic-lanceolate, acute, 1.8- 3.7 cm long, scattered on the peduncle and one or two at its base; raceme globose to subcylindric, dense, 12- to 20-flowered; rachis 1-3(-5) cm long; floral bracts caducous, elliptic-lanceolate, acute or acuminate, 10-20(-40) × 7-8(-20) mm, hyaline, white. Flowers 17-26 mm across, yellow, hypochile and side lobes of the lip sometimes with a faint red-purple tinge. Ovary indistinguishable from the pedicel, (10-)14-18(-25) mm long. Sepals elliptic-lanceolate, acute, acuminate or aristate, 3- to 5-veined; median sepal (12-)14-16(-18) × 4-6.2(-8) mm; the laterals similar but slightly narrower. Petals oblanceolate to somewhat spathulate, acute, 3- to 5-veined, (11-)12-15(-18) × (2-)4.2- 4.6(-6) mm. Lip 3-lobed, 10-13 × 8.6-13.8 mm, spurred; midlobe broadly rounded to subquadrate, shallowly emarginate or truncate, 4.5-5(-6) × (4-)5- 6(-7) mm, apex obtuse or emarginate, straight or recurved; side lobes ovate to subtriangular, erect, 3.5-9 × 3-3.5 mm, with two diverging fleshy triangular or half-moon shaped lamellae between them which are highest at the distal end; spur cylindric or slightly clavate, straight, 8.5-15(-20) mm long. Gynostemium (8.5-) 12-13 mm long, straight or curved, united with the lip for 3-4.5 mm. Fruits ellipsoid, 10-11 × 5-6 mm.

DISTRIBUTION AND PHENOLOGY

In Thailand only recorded in the North-East. Generally widespread in continental Asia from the Himalayas to Indochina and S China; also found in S Japan and Taiwan. Found in broad-leaved or mixed forest, often with bamboo, from 1350 to 1530 m.

REMARKS

Phaius epiphyticus Seidenf. is in its vegetative and floral structure identical with Calanthe densiflora and is therefore considered as conspecific here, as also suggested by P. Ormerod (hand-written letter dated 7.VII. 1998 in the Seidenfaden working files in Copenhagen) and P. Cribb (pers. comm. on 24.XI.2008). The origin of the species name epiphyticus is not clear – in the aforementioned letter Seidenfaden himself had noted that there was no definitive evidence that the plant was indeed an epiphyte.